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Full text of "The manufacture and properties of iron and steel"

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INTRODUCTION.            '                                  29
The disregard of specifications by the manufacturer often appears in substituting Bessemer metal for open-hearth, or basic steel in place of acid, and there are cases where such material has been accepted. Needless to say that by so doing the engineer places himself in an unfair relation to every works which made a bid on the better quality of material, and needless to say that such a transaction casts a shadow of doubt over every clause in future contracts.
Such a concession is an acknowledgment that the specifications were written in ignorance, and while such error should be recognized when it exists, it would also be well if carefully considered requirements were enforced. Often there are details which are the result of carelessness. In a large contract embracing a number of foundation bolts and similar forgings, part were of steel from 70,000 to 80,000 pounds tensile strength, while the rest were from 72,000 to 82,000. The cause of this absurdity was a change in management with a revision of the specifications, and while the requirements for a certain portion were allowed to remain unaltered, new regulations were made for the rest of the work. The divergence was an accident, and yet the inspector refused to accept steel running 71,500 pounds for one bolt, while for another he would accept 71,000 pounds.
Mistakes in specifications call for discretionary power on the part of the inspector, and such power is needed also to settle questions of detail arising in the manufacture. Thus, during the construction of a large train shed, a few angles were needed of a. special section not on hand. The time to put in rolls to make them would have cost many times what the angles were worth, but it was necessary to make a hard fight for permission to use angles of the same section and the same analysis and character, but which were one-sixteenth inch thicker than called for. It is conceivable that in a war vessel, where every pound is figured upon, an inspector would refuse to accept anything beyond the limit, and in the building of a long-span bridge the weights of materials should be carefully watched; but that the same care is necessary, in the fa.ce of great expense, in a small-span train shed, is a conceit which could only arise from misguided honesty.
A more striking example occurred in the assembling of the angles and plates composing certain large members where it was necessary to use a few long, narrow pieces not over one-sixteenth, of